Many types of medical equipment are subject to various safety regulations and/or requirements to ensure patient safety standards are met. One type of safety regulation to which electrically powered medical equipment is subject is patient leakage limitations. For example, IEC60601-1 3rd edition (Section 8.7 entitled: Leakage Currents and Patient Auxiliary Currents) testing defines the testing and current leakage limits for a type CF (cardiac floating) Applied part. As part of this standard, total patient leakage current is limited to 100 microamps (μA), and the single fault condition patient leakage current is limited to 50 μA. Individual items of medical equipment are typically designed to meet these (and other) safety limitations such that they can be safely incorporated and used with various medical equipment systems.
In some environments, it is not uncommon to combine multiple items of medical equipment together in a medical cart or cabinet to form a consolidated medical system that may optionally be portable to enhance usability. In the context of a cardiac electrophysiology laboratory, for example, it may be useful to organize the hardware used for performing electroanatomical mapping and ablation procedures into a single, medical cart or cabinet in order to reduce clutter and improve usability of the equipment in the laboratory. The consolidated medical system must still meet the applicable safety regulations and standards.
In many circumstances, an isolation transformer is inserted between the alternating current (AC) power source and one or more pieces of the equipment forming the consolidated medical system in order to reduce noise and leakage currents. Such isolation transformers, however, are often relatively large in size in order to handle the power requirements of all of the medical equipment in the consolidated system. The large surface area of such transformers allows for capacitive coupling of 60 hertz (Hz) fault power between the primary and secondary sides of the isolation transformer. This capacitive coupling can potentially result in the generation of leakage currents on the output side of the power supply, making it difficult to maintain the patient leakage current below the required maximum levels.